The South Korean Embassy in Beijing has warned its nationals to be wary of a scam involving North Korea's "old bank notes," which had been issued before the North's botched currency reform in 2009, an embassy official said Thursday.

Some foreign scammers, mostly Indonesians posing as businessmen, have recently approached South Korean nationals living in Beijing and tricked them into buying the North Korean bank notes by offering significantly lower prices than market value.

"The North Korean currency is being only circulated inside North Korea and is not used internationally," the official said on the condition of anonymity because he is not authorized to speak to media.

"So, the North Korean currency notes are useless," he said, adding that such an offer is a "100 percent scam."

The scammers typically fool people into buying a large amount of the North Korean bank notes with a face value of 5,000 North Korean People's Won (won) at 30 percent to 40 percent cheaper than market value, according to the official.

North Korea's centrally planned exchange rate is 130 won to $1, but black-market rates are some 8,500 won to $1.

It remains unclear how such a large amount of old North Korean bank notes were flown into Beijing, he said, adding that similar scams were reported in Indonesia.

The South Korean Embassy issued a public warning against such scams and encouraged its nationals to report them to authorities, the official said. (Yonhap)